Add role annotations to SNat, SSymbol and SChar
Add role annotations to SNat, SSymbol and SChar
Ticket #23454 (closed) explained it was possible to implement unsafeCoerce because SNat was lacking a role annotation.
As these are supposed to be singleton types but backed by an efficient representation the correct annotation is nominal to ensure these kinds of coerces are forbidden.
These annotations were missed from https://github.com/haskell/core-libraries-committee/issues/85 which was implemented in 532de368.
Fixes #23454 (closed)